1. Field of the Invention
The present invention relates to the coupling for a tractor and a trailer especially as used as a fire fighting method in the wildland and forest fire fighting industry.
2. Description of Prior Art
Ecologically sensitive wild land fire fighting has been an unresolved issue for some time now. This was particularly evident during the great Yellowstone wildfire in 1993. In wildland fire fighting there are primarily three distinct fire fighting methods employed on the ground.
The first method is the use of the continuous track vehicle, most frequently in the bulldozer configuration, in which fire break lines are scarred into the earth displacing dirt, trees, and vegetation. This fuel mass is removed from the fire path deterring further travel of fire. Although highly effective as a fire break method the dozing of the earth is believed by many to be a major source of problems after the fire. Long term effects include erosion, eradication of subterranean plant life, disturbing delicate ecosystems, and the inadvertent creation of undesirable roads.
In environmentally sensitive areas human handwork is required. In this second method wild land fire fighters and smoke-jumpers battle fires in these areas at great personal risk. They use hand hoes and shovels, along with chain saws and hotpacks to start back burn fires. The result is the same, to remove or consume the fuel mass in the path of oncoming fire. Death of firefighters is common in this method.
The third method is the use of small tender trucks or trailers towed behind trucks with limited and meager water capacity that are able to access small spots fires with an onboard hand water line. Prior art reference Wajax-Pacific Fire Equipment, May 1993 catalog p. 39, shows such a small portable trailer usable for spot fires.
A primary object of the invention is a novel fire fighting method that allows a fire tractor to tow an over-the-road tank trailer and deliver fire fighting foam to be sprayed in quantities adequate to provide a foam fire line precluding destructive method of dozing or the slow and dangerous work of a hand crew.
A further object of the present invention is to make the tank water also available off road to smaller tender tricks to replenish their supplies and for conventional water fire fighting means.
A further object of the present invention is the provision of a hitch assembly to allow releasable and locking fifth wheel plate and kingpin coupling or connecting of the fire tractor to a tank for carrying water or other fluid type in the configuration of an over-the-road semi trailer.
A further object of the present invention is the provision of a hitch assembly to allow a secondary hitch means to allow coupling to the drawbar eye on an over-the-road configuration A-train trailer that has forward and rearward axles or a plurality of axles at the forward or rearward end.
A further object of the present invention is a means to facilitate a plurality of tanks, in the configuration of over-the-road trailers, to be towed simultaneously for even greater fire fighting capacity.
Off road tractors have the power to move large and heavy loads, however they are not equipped to pull a conventional over-the-road semi trailer. Wheeled tractors are common especially to the agricultural industry and inexpensive. Prior art reference U.S. Pat. No. 5,090,720 adapting them for hauling over-the-road trailers using fifth wheel plate and kingpin coupling requires a type of wheeled dolly that will carry all or most of the vertical kingpin load. A great disadvantage is encountered in this dolly method because a forward articulation point is provided ahead of the rearward articulation point making the act of backing up the tractor, dolly, and trailer difficult and in some cases impossible. This is aggravated by the short radius distance between the hitch pin and the dolly fifth wheel plate.
Prior art reference U.S. Pat. No. 4,887,831 of Edwards is a further attempt to use the dolly method to employ a coupling method in the over-the-road kingpin configuration. Edwards in an attempt to provide a stable towing system for agricultural mobile equipment invented a unique dolly after he failed in his attempt to modify a conventional field vehicle to include a releasable fifth wheel.
The successful application of the present invention and the failure of Edwards should be apparent to one skilled in the art, as Edwards attempted to use a releasable fifth wheel to drag mobile equipment. To maximize field usage, agricultural equipment turns sharply at the end corners of a field. This essentially puts a jack knife condition between the tractor and the mobile equipment and shock loading into the fifth wheel plate, attaching means, and locking jaws. Towing equipment that is not equipped with spring of other type of suspension is jerky in a field application and causes undesirable loading of the fifth wheel plate. The fifth wheel plate is designed to accept a heavy vertical and horizontal loads, essentially static in nature. Edwards' attempt misused a highway type releasable fifth wheel causing it to fail to function satisfactorily under his three enumerated criteria. The successful application of the present invention described further in the preferred embodiment is shown to be unobvious in light of Edwards' attempt.
Prior art reference U.S. Pat. No. 5,297,911 of Powel is a lifting and tilting vehicle and fifth wheel plate that is necessarily employed from a fork lift mast. A vehicle of the claimed description is neither known nor desirable to the fire fighting industry with its complicated two end attachment arms and limited rotating elongate member lifting system. Continuous track vehicles available for use in fighting wildland fires come from two arenas, fire company owned machines and seasonal contracts with local logging and excavation companies who typically deploy their equipment to the fire location via over-the-road truck and lowboy semi trailer. Therefore one could reasonably expect bulldozers, excavators, and log skidders to be available and not a massive continuous track forklift.
Fifth wheel plate and kingpin type hitch coupling are within the scope of the present invention and prior art descriptions. Prior art reference U.S. Pat. No. 4,199,168 of Bush and Martin is an example of such a connecting hitch plate. A fifth wheel plate and specific attaching means which the letters of patent of Bush and Martin describe are cited here and further referred to in the preferred embodiment of the present invention. The particular attaching means and suspension system enumerated by Bush and Martin need not be employed to be within the scope of the present invention.